Valvular heart disease is recognized as a common disease in the elderly population. Prevalence of valvular heart diseases increases indeed with age, from 0.7% in 18-44 year olds to 13.3% in the 75 years and older group (Nkomo, V T. et al., Burden of valvular heart disease: a population-based study, The Lancet, Volume 368, Issue 9540, Pages 1005-1011, 2006).
A mammalian heart valve comprises four heart valves which determine the pathway of blood flow through the heart. A mammalian heart generally comprises two atrioventricular valves namely the mitral valve and the tricuspid valve, which are located between the atria and the ventricles and prevent backflow of blood from the ventricles into the atria; and two semilunar valves (also known as arterioventricular valves) namely the aortic valve and the pulmonary valve, which are located in the arteries leaving the heart and prevent backflow of blood from the arteries into the ventricles.
The mitral valve, also known as the left atrioventricular valve, is composed of two valve leaflets (anterior and posterior), an annulus, a supporting chordae tendinae, and papillary muscles. The tricuspid valve, also known as the right atrioventricular valve, is made up of three valve leaflets (anterior, posterior and septal), an annulus, a supporting chordae tendinae, and papillary muscles. The aortic valve is composed of three valve leaflets (right, left and posterior) and an annulus. The pulmonary valve is made up of three valve leaflets (right, left and anterior) and an annulus. The fibrous aortic annulus, the fibromuscular pulmonary annulus and the muscular tricuspid and mitral annuli are linked to the leaflets. As the heart beats, the leaflets open and close to control the flow of blood. The leaflets of the atrioventricular valves are prevented from prolapsing into the atrium by action of the papillary muscles, connected to the leaflets via the chordae tendinae.
Mitral regurgitation—the mitral leaflets do not close properly leading to abnormal leaking of blood—is the most commonly occurring valve abnormality. In the US, in every age group, mitral regurgitation is the most common valvular disorder with a global prevalence of 1.7%, increasing to 10% in adults above 75 years old. (Nkomo, V T. et al., Burden of valvular heart disease: a population-based study, The Lancet, Volume 368, Issue 9540, Pages 1005-1011, 2006). Besides mitral regurgitation, conditions affecting the proper functioning of the mitral valve also include mitral valves stenosis—the opening of the mitral valve is narrowed leading to systolic function deterioration. Aortic valve, pulmonary valve and tricuspid valve may also be affected by regurgitation and stenosis. Heart valve regurgitation and stenosis have strong humanistic outcomes.
Typically, treatment for heart valve regurgitation or stenosis involves either administration of diuretics and/or vasodilators to reduce the amount of blood flowing back, or surgical procedures for either repair or replacement of the heart valve. Repair approach involves cinching or resecting portions of a dilated annulus, for example by implantation of annular rings which are generally secured to the annulus or surrounding tissue. Alternatively, more invasive procedure involves the replacement of the entire heart valve; mechanical heart valves or biological tissues are implanted into the heart in place of the native heart valve. These invasive procedures are performed either through large open thoracotomies or by percutaneous route.
However, in many repair and replacement procedures, the durability of the devices, or the improper sizing of annuloplasty rings or replacement heart valves, may result in additional issues for the patients. For this reason a significant part of patients with valvular heart diseases are denied for surgery. Indeed, despite guidelines for the management of patients with valvular heart disease, 49% of patients with severe mitral regurgitation, assessed by Doppler-echocardiography, are not referred to for surgery; mainly because of their advanced age, the presence of comorbidities, or impaired left ventricular ejection fraction (Mirabel, M. et al., What are the characteristics of patients with severe, symptomatic, mitral regurgitation who are denied surgery, European Heart Journal, Volume 28, Pages 1358-1365, 2007).
Less invasive approaches recently implemented involve pre-assembled, percutaneous expandable prosthetic heart valves. U.S. Pat. No. 5,840,081 discloses a method for implanting an aortic valve mounted on an expandable stent. However, human anatomical variability makes it difficult to design and size a prosthetic heart valve having the ability to conform to a heart annulus. Especially percutaneous atrioventricular valve replacement is a real challenge as the native atrioventricular valves annuli have a non-circular, non-planar, saddle-like geometry often lacking symmetry.
Technical Issue
According to the Applicant, as a prosthetic heart valve needs a stable and symmetric support during the cardiac cycle to ensure proper functioning, there is a need for devices enabling proper anchoring of prosthetic heart valve within the native heart valve. There is also a continued need to provide a prosthetic heart valve avoiding or preventing trauma to the surrounding tissue and ensuring proper functioning even in case of cardiac valve fibrosis.
Current devices developed for percutaneous heart valve replacement were found unsuitable for the following reasons:                Firstly, many of these existing devices support the prosthetic heart valve while contacting the annulus; thereby directly transferring to the prosthetic heart valve many of the distorting forces exerted by the surrounding tissue and blood as the heart contracts during each cardiac cycle. As cardiac replacement devices further comprise heart valves which require a substantially symmetric, cylindrical support around the prosthetic heart valve for proper opening and closing of the leaflets over years of life, when these devices are subjects to movement and forces from the annulus and other surrounding tissues, the prostheses may be compressed and/or distorted, causing the prosthetic leaflets to malfunction. For example International Patent Application WO 2009/106545 discloses an expandable stent for the positioning and anchoring of valvular prosthesis in an implantation site in the heart of a patient in the treatment of a narrowed cardiac valve (stenosis) or a cardiac valve insufficiency (regurgitation). In this application, the stent comprises at least one fastening portion via which the valvular prosthesis can be connected to the stent. This stent is designed as a single wall structure with a circular section and does not address the issue of geometrical unpredictability. Such device does not really prevent paravalvular leakage. Indeed, as the supporting tissue does not offer a stable circular section, junction between the stent and the native heart valve is not achieved on the entire periphery of the heart valve. Moreover, with a single wall structure the stent does not mechanically isolate the prosthetic heart valve from the surrounding native tissues, thereby preventing proper functioning of the prosthetic heart valve during each cardiac cycle.        Secondly, common stents provide radial anchorage and may migrate or slip relative to the heart wall due to blood flow, movements and forces from the annulus and other surrounding tissues. Some existing devices may overcome this drawback by providing an anchoring device comprising a plurality of hook-shaped elements as disclosed in International Patent Application WO 2001/64137. However, this circular device is inflexible and the seal between the anchoring device and the native heart valve and surrounding tissues is hard to achieve. Furthermore, radial support of the surrounding tissue of an atrioventricular valve is significantly lower than radial support of the surrounding tissue of an aortic valve. Therefore radial anchorage of a stent designed for aortic valve may be insufficient when used for atrioventricular valve replacement.        Thirdly, minimally invasive procedure, without direct vision of the surgical site, strongly relies on cardiac surgeon's skills. The prosthetic heart valve must be able to be maneuvered to the greatest possible extent during implantation procedure so as to ensure optimum positioning accuracy. Misalignment of the anchoring device may indeed lead to leakage and unsealing of the device.        
International patent application WO 2006/128185 discloses an intravascular cuff, with two mushroom-like ends which, upon deployment, trap the native heart valve. The two ends are released sequentially: in a first step the first end is expanded and may abut against the native heart valve for ensuring proper placement; and in a second step the second end is expanded, thereby completely encasing the native heart valve in the cuff. However, WO 2006/128185 does not disclose a double-wall device at the height of the prosthetic heart valve, but only at the two ends. On a practical point of view, WO 2006/128185 discloses the replacement of the native heart valve in two steps. Firstly, the cuff is released from a first catheter and traps the native heart valve and secondly, an expandable prosthetic heart valve is released from a second catheter inside the lumen of the expanded cuff. Upon expansion of the prosthetic heart valve inside the cuff from the second catheter, the prosthetic heart valve expands the central lumen of the cuff and presses against the native heart valve (cf. [0026] and FIGS. 6 and 7). Consequently, the cuff disclosed by WO 2006/128185 directly transfers the forces exerted by the native heart valve and surrounding tissue to the prosthetic heart valves. Furthermore, the shape of the mushroom-like ends do not closely fits the native surrounding tissue along their entire length.
The present invention addresses and intends to correct the drawbacks of the devices of the prior art. The present invention thus relates to a system for anchoring a prosthetic heart valve inside a heart (hereinafter referred to as the anchoring system) comprising a self-expanding anchoring device (hereinafter referred to as the anchoring device) and a compressible and expandable prosthetic heart valve support—including a prosthetic heart valve—attached to the anchoring device. The anchoring device of the invention comprises: an extraventricular part, a ventricular part comprising a double wall and a predefined V-shaped groove formed between the extraventricular part and the ventricular part. Thus, the anchoring device of the invention (i) provides a geometrical anchorage with both radial sealing and longitudinal support, (ii) prevents direct transfer to the prosthetic heart valve of the forces exerted by the surrounding tissue as the heart contracts during each cardiac cycle and (iii) mechanically isolates the prosthetic heart valve from the surrounding tissue.